Soil Solarization ?

Richmond Hill, GA(Zone 8b)

Hi Marsh! I was wondering.. do you ever solarize your soil? If you do, how long do you leave your plastic on? I've always left my plastic on for 6-8 weeks but I wonder if the 8 weeks is really necessary. Also, I just read an article that said in soil solarization the soil is heated to a 18 inch depth but I wonder if that's true. Is it? Thank you for sharing you knowledge with us. :)

Here's the article on soil solarization that mentions how deep the soil is actually heated.


Santa Barbara, CA


I have solarized in the past but am currently in a climate with cool, often overcast days.

Your link generally has the right idea; even the heating to 10-12 inches is possible with the right soil, solar conditions, and installation. Eighteen inches is stretching. Unfortunately, 100F is not especially high nor very damaging to most soil life. Sustained temperatures over 125F will kill or weaken many weed seeds and some fungal diseases; temps of 140F will eliminate most of the other microbes of concern without killing all life.

I do urge a minimum of 6 weeks-- takes a while to kill the tougher things-- and longer if sunlight and weather conditions are less favorable.

Richmond Hill, GA(Zone 8b)

Lately here in Georgia many folks have been having a terrible time with tomato blight. They've had their whole tomato crop wiped out. They probably introduced the disease into their garden by accident when they bought some infected plants from a nursery or garden center. I've always heard that once you get it, it will live in your soil for years and years and it's best to plant your crop in another location. I wonder if soil solarization would help. It might take several consecutive solarization treatments...tilling the soil in between each time to get down deeper into the soil. What do you think, Marsh?


Santa Barbara, CA

Hey, Terri, I somehow missed your question. In the olden days of the mold-board plow, the soil was inverted, thus burying the diseased plant materials and surface spores down a foot or so. I have tomato diseases in every part of my farm but not every crop is affected.

Solarization might work if you are careful about drainage and about not bringing contaminated soil and tools to the planting area. I suspect that the heavy and long rains in GA kicked off blights. Phytopthera (sp) and Fusarium diseases are specially severe when the root systems are starved for air.

Lyndeborough, NH


There was an article a NCSU that said the soil temp has got to reach 125F for 6 weeks. I thought they said this only
reaches 1/2 to 1 in. Although most pathogens live only in this range.

They said not feasable in NC maybe in FLA.

Sometimes you can get by with deep plowing or the home gardener double digging. IE bury the top soil a shovelfull deep.

In the north a total waste of time. Not enough solar engery to get it done.


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